Vacuum cleaners can include an agitator for agitating debris on a surface to be cleaned so that the debris is more easily ingested into the vacuum cleaner. In some cases, the agitator comprises a motor-driven brushroll that rotates within a base assembly or floor nozzle. Agitator height control mechanisms have been developed to allow a user to selectively adjust the height of the agitator relative to the surface to be cleaned to allow in accordance with the type of floor surface, i.e. carpet, deep carpet, bare floor, etc. In many such control mechanisms, the height of the agitator is adjusted by raising or lowering the entire base assembly or floor nozzle relative to the floor surface. This results in a change in the distance between the suction nozzle and the floor surface. As the distance increases, i.e. when the agitator is raised, the working air velocity is decreased and the vacuum cleaner can experience a loss of suction, resulting in reduced efficiency and poorer cleaning performance.